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Water purification is crucial for hemodialysis (HD) as patients are exposed to large amounts of water with each treatment. Conventional hemodialysis (CHD) patients are typically exposed to more than 400 L of water each week, while for home hemodialysis (HHD) water exposure can vary from 150 L to significantly more than 400 L per week depending on the HD prescription and the dialysis system.1 There are many substances that must be removed from the water supply to make it safe for dialysis. Water purification systems consist of a series of components that remove contaminants via different mechanisms. Regular monitoring of its components and of the product water is essential for ensuring proper function of the water system.2 Failure to adequately treat the water supply can lead to serious adverse effects, including death.3,4 While water standards are the same for CHD and HHD, some of the dialysis systems used for HHD differ from conventional machines. Water treatment is reviewed in this chapter with a focus on issues specific to HHD.
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GENERAL CONSIDERATIONS
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HHD can be done in nearly any home with electricity and water supply. A home visit should be conducted for any prospective patient to evaluate the suitability of the home for HHD. Testing of the water source to ensure it meets drinking water regulations or source water requirements is also necessary. In order to install a dialysis system in a home, some modifications must be made—these vary by the type of machine. Some homes may require alterations to the electrical supply, such as installation of a ground fault circuit interrupter outlet where the dialysis machine will be located in the home, or provision of a backup power supply.5 Nearly all homes will require plumbing modifications. The costs associated with any modifications are borne by the dialysis provider and the patient does not incur any cost. If a patient does not own his or her home, such modifications must be approved by the landlord. Occasionally, a patient is unable to obtain permission to make modifications and therefore is unable to do HHD.
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HOME HEMODIALYSIS MACHINES AND WATER PURIFICATION SYSTEMS
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CHD machines are too large and heavy to be used in the home, and water purification systems for in-center HD units occupy very large spaces. HHD systems are scaled down in size and simplified for home use. The first machines used for HHD were conventional machines adapted for home use—an example of such a machine is Fresenius Medical Care’s 2008K@home HD machine, which is similar to its in-center HD machines in size and appearance.6 It utilizes a separate reverse osmosis (RO) system for online water purification. More recently, machines designed specifically for HHD have been developed.7 These include NxStage Medical Inc.’s System One, Quanta Dialysis Technologies Ltd.’s SC+, the Physidia S3 monitor, and Outset Medical Inc.’s Tablo system.8,9 The ...